An arranger keyboard can be fun and useful for learning.
The auto-accompaniment provides drums, bass, etc. while you play, in a style of your choice. Arrangers typically come with hundreds of musical styles to choose from. Your left hand is used to specify the harmony. If you don’t know any chords, one left hand note will default to a major triad (chord). The more chords you learn, though, the more fun you’ll have.
So while you’ll need to develop some hand independence to get good use out of an arranger, you won’t need as much as someone who has committed to playing the Bach Inventions, Chopin etudes, or anything like that, in front an audience. You just need enough to be able to change your left hand chord shape in time with the auto-accompaniment, while playing the melody or whatever with your right hand.
So if your goal with the keyboard is just to upgrade from the hunt-and-peck style of note entry on a keyboard, to a more efficient skill level - and you don’t aspire to be a world class concert pianist - this could be a useful investment.
Oh and a lot of arranger keyboards double as linear MIDI sequencers.